The reaction of highly electrophilic azolo[b]pyridines with pyrrole and indole derivatives as nucleophiles afforded 1,4-addition products to the pyridine ring. The reactions of structurally similar meta-dinitrobenzo-fused heterocycles (furoxan, thiadiazole, selenadiazole, pyridine) with C-nucleophiles (salts of ketones and 2-nitropropane) gave stable anionic σ-complexes in high yields. Their oxidation led to rearomatization with the formation of the corresponding products of substitution of a hydrogen atom with the nucleophile. The oxidation was generally accompanied by the decomposition of σ-complexes into the parent compounds.
                                    高亲电性的偶氮并[b]
吡啶与作为亲核体的
吡咯和
吲哚衍
生物反应,得到了
吡啶环的 1,4 加成产物。结构类似的元
二硝基苯并融合杂环(
呋喃、
噻二唑、
硒二唑、
吡啶)与 C-亲核物(酮和 
2-硝基丙烷的盐类)的反应产生了高产率的稳定阴离子 σ-络合物。它们在氧化过程中会发生重气化,形成相应的氢原子与亲核物取代的产物。氧化通常伴随着 σ-络合物分解为母体化合物。